Freeze plug suppressors in 22 and 30 cal. The 22 is quieter than two commercial suppressors I've compared it with. Never tried a commercial 30 to compare, but no complaints with 300 BLK. One of the best projects to spend my time on! Plenty of build info online. These were built before the changes to gun trusts, and built them Form 1 for faster stamp arrival time, which I think was around 90 days. Plus, less than $100 total for each was hard to pass up (plus tax stamps of course).